WO2011005032A2 - Method and apparatus for carrier scheduling in a multi-carrier system - Google Patents

Abstract

Provided are a method and apparatus for carrier scheduling in a multi-carrier system. A terminal receives information, which indicates whether or not to perform a cross carrier scheduling process, from a base station. If it is determined, by means of said information, that the cross carrier scheduling process is to be performed, the terminal receives scheduling information on a second downlink carrier via a first downlink carrier, and receives downlink data from the second downlink carrier.

Description

Carrier scheduling method and apparatus in multi-carrier system

The present invention relates to wireless communication, and more particularly, to a method and apparatus for performing scheduling between a plurality of carriers in a wireless communication system supporting multiple carriers.

The 3rd Generation Partnership Project (3GPP) long term evolution (LTE), an improvement of the Universal Mobile Telecommunications System (UMTS), is introduced as a 3GPP release 8. 3GPP LTE uses orthogonal frequency division multiple access (OFDMA) in downlink and single carrier-frequency division multiple access (SC-FDMA) in uplink. 3GPP LTE employs multiple input multiple output (MIMO) with up to four antennas. Recently, a discussion on 3GPP LTE-Advanced (LTE-A), an evolution of 3GPP LTE, is underway.

Techniques introduced in 3GPP LTE-A include carrier aggregation, relay, and the like. The 3GPP LTE system is a single carrier system supporting only one bandwidth (that is, one component carrier) of {1.4, 3, 5, 10, 15, 20} MHz. However, LTE-A introduces multiple carriers using carrier aggregation. A component carrier (CC) is defined as a center frequency and bandwidth. Multi-carrier system is to use a plurality of CC having a bandwidth less than the total bandwidth.

As a plurality of CCs are used, a transmitting station (for example, a base station or repeater) transmits a channel downlink information for a downlink data channel or a downlink physical control channel for transmitting uplink data channel information. It is necessary to inform the receiving station (for example, a repeater or a terminal) about which CC is transmitted through a plurality of CCs.

A method and apparatus for performing scheduling among a plurality of CCs in a wireless communication system supporting carrier aggregation.

In a multi-carrier system according to an aspect of the present invention, a carrier scheduling method includes receiving information indicating whether cross-carrier scheduling is performed from a base station; If it is determined that cross-carrier scheduling is performed based on the information, receiving scheduling information on a second downlink carrier through a first downlink carrier; And receiving downlink data from the second downlink carrier, wherein information indicating whether to perform the cross carrier scheduling is received as an upper layer signal.

If it is determined that cross carrier scheduling is performed based on the information, receiving scheduling information on a first uplink carrier through a first downlink carrier; And transmitting uplink data to the base station through the first uplink carrier.

Information indicating whether the cross carrier scheduling is performed may be received through a radio resource control (RRC) message.

The RRC message may further include index information for the first downlink carrier.

The RRC message may further include index information for the second downlink carrier.

The scheduling information for the second downlink carrier received through the first downlink carrier may include a carrier indication field (CIF) indicating the second downlink carrier. The CIF may be represented as an absolute index or a logical index of the second downlink carrier.

The first downlink carrier may be a predetermined downlink carrier file.

The control channel transmitted on the first downlink carrier or the second downlink carrier may be set to an independent number of OFDM symbols in the time domain.

Cross-carrier scheduling may be performed after N (N is a natural number of 1 or more) subframes from a subframe that receives information indicating whether to perform cross-carrier scheduling from the base station.

In a multi-carrier system according to another aspect of the present invention, a terminal performing cross carrier scheduling includes: an RF unit for transmitting and receiving a radio signal; And a processor connected to the RF unit, wherein the processor receives information indicating whether to perform cross-carrier scheduling from a base station, and if it is determined that cross-carrier scheduling is performed based on the information, the processor determines a first downlink carrier. Receiving scheduling information on a second downlink carrier and receiving downlink data on the second downlink carrier, information indicating whether to perform cross-carrier scheduling is received as an upper layer signal.

In a wireless communication system using a plurality of CCs and supporting carrier aggregation, it is possible to know through which CC the scheduling information is transmitted, and scheduling can be performed between the CCs.

1 illustrates a wireless communication system.

2 shows a network system supporting a repeater.

FIG. 3 shows a radio frame structure of 3rd Generation Partnership Project (3GPP) long term evolution (LTE).

4 is an exemplary diagram illustrating a resource grid for one downlink slot.

5 shows a structure of a downlink subframe.

6 shows a structure of an uplink subframe.

7 shows transmission and reception of data in 3GPP LTE.

8 is an exemplary diagram illustrating monitoring of a PDCCH.

9 shows an example of a transmitter and a receiver in which multiple MACs operate multiple carriers.

10 shows an example of a transmitter and a receiver in which one MAC operates multiple carriers.

11 shows an example of a multi-carrier system.

12 shows an example of operation of a multi-carrier.

13 shows an example of cross carrier scheduling.

14 shows uplink synchronous HARQ in 3GPP LTE.

15 shows an example of a CC set.

16 is a block diagram illustrating a wireless communication system in which an embodiment of the present invention is implemented.

1 illustrates a wireless communication system.

Referring to FIG. 1, the wireless communication system 10 includes at least one base station 11 (BS). Each base station 11 provides a communication service for a particular geographic area (generally called a cell) 15a, 15b, 15c. The cell can in turn be divided into a number of regions (called sectors). The user equipment (UE) 12 may be fixed or mobile, and may include a mobile station (MS), a user terminal (UT), a subscriber station (SS), a wireless device, a personal digital assistant (PDA), It may be called other terms such as a wireless modem and a handheld device. The base station 11 generally refers to a fixed station communicating with the terminal 12, and may be referred to as other terms such as an evolved-NodeB (eNB), a base transceiver system (BTS), an access point, and the like. have.

2 shows a network system supporting a repeater. A repeater is a technique for relaying data between a terminal and a device station. A network node that performs a relay function is called a relay node (RN). A base station managing one or more RNs is called a donor BS (DBS).

The air interface between the terminal and the RN is called a Uu interface, and the air interface between the RN and the base station is called an Un interface. The link between the terminal and the RN is called an access link, and the link between the RN and the base station is called a backhaul link.

The RN manages the terminal on behalf of the base station. The terminal may be transparently provided from the base station through the RN. In view of a base station, an RN may be provided with a service as a terminal and may be provided with a service as a base station of the terminal.

Hereinafter, unless otherwise specified, downlink (DL) means communication from a base station to a terminal, and uplink (UL) means communication from a terminal to a base station.

However, the present invention can be applied to a network system supporting a repeater. In the access link, downlink is communication from RN to terminal, and uplink is communication from terminal to RN. In the backhaul link, downlink is communication from the base station to the RN, and uplink is communication from the RN to the base station.

FIG. 3 shows a radio frame structure of 3rd Generation Partnership Project (3GPP) long term evolution (LTE). This can be found in sections 4.1 and 4.2 of 3GPP TS 36.211 V8.5.0 (2008-12) "Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation (Release 8)". have.

Referring to FIG. 3, a radio frame consists of 10 subframes and one subframe consists of two slots. One subframe may have a length of 1 ms, and one slot may have a length of 0.5 ms. The time taken for one subframe to be transmitted is called a transmission time interval (TTI). TTI may be a minimum unit of scheduling.

One slot may include a plurality of orthogonal frequency division multiplexing (OFDM) symbols in the time domain. The OFDM symbol is used to represent one symbol period since 3GPP LTE uses OFDMA in downlink and may be called another name. For example, it may be referred to as an SC-FDMA symbol. One slot includes 7 OFDM symbols as an example, but the number of OFDM symbols included in one slot may vary according to the length of a cyclic prefix (CP).

According to 3GPP TS 36.211 V8.5.0 (2008-12), one subframe includes 7 OFDM symbols in a normal CP and one subframe includes 6 OFDM symbols in an extended CP.

The structure of the radio frame is only an example, and the number of subframes included in the radio frame and the number of slots included in the subframe may be variously changed.

4 is an exemplary diagram illustrating a resource grid for one downlink slot.

One slot includes a plurality of orthogonal frequency division multiplexing (OFDM) symbols in the time domain. A resource block (RB) includes a plurality of consecutive subcarriers in one slot in resource allocation units.

Here, one downlink slot includes 7 OFDM symbols and one resource block includes 12 subcarriers in a frequency domain, but is not limited thereto.

Each element on the resource grid is called a resource element, and one resource block includes 12 × 7 resource elements. The number N ^DL of resource blocks included in the downlink slot depends on the downlink transmission bandwidth set in the cell. The resource grid described in FIG. 3 may also be applied to uplink.

As disclosed in 3GPP TS 36.211 V8.5.0 (2008-12), a physical channel in LTE is a physical downlink shared channel (PDSCH), a physical downlink shared channel (PUSCH), and a physical downlink control channel (PDCCH), which is a control channel. It may be divided into a Physical Control Format Indicator Channel (PCFICH), a Physical Hybrid-ARQ Indicator Channel (PHICH), and a Physical Uplink Control Channel (PUCCH).

5 shows a structure of a downlink subframe.

The subframe includes two consecutive slots. The maximum 3 OFDM symbols of the first slot in the subframe are the control region to which the PDCCH is allocated, and the remaining OFDM symbols are the data region to which the PDSCH is allocated. In addition to the PDCCH, the control region may be allocated a control channel such as PCFICH and PHICH.

The PCFICH transmitted in the first OFDM symbol of a subframe carries a control format indicator (CFI) regarding the number of OFDM symbols (that is, the size of the control region) used for transmission of control channels in the subframe. The terminal first receives the CFI on the PCFICH, and then monitors the PDCCH.

The PHICH carries a positive-acknowledgement (ACK) / negative-acknowledgement (ACK) signal for an uplink hybrid automatic repeat request (HARQ). The ACK / NACK signal for the uplink data transmitted by the terminal is transmitted on the PHICH.

Control information transmitted through the PDCCH is called downlink control information (DCI). The DCI may include resource allocation of the PDSCH (also called downlink grant), resource allocation of the PUSCH (also called uplink grant), a set of transmit power control commands for individual UEs in any UE group, and / or VoIP (Voice). over Internet Protocol).

The uses of the DCI format are classified as shown in the following table.

DCI format	Contents
DCI format 0	Used for PUSCH scheduling
DCI format 1	Used for scheduling one PDSCH codeword
DCI format 1A	Used for compact scheduling and random access of one PDSCH codeword
DCI format 1B	Used for simple scheduling of one PDSCH codeword with precoding information
DCI format 1C	Used for very compact scheduling of one PDSCH codeword
DCI format 1D	Used for simple scheduling of one PDSCH codeword with precoding and power offset information
DCI format 2	Used for PDSCH scheduling of terminals configured in closed loop spatial multiplexing mode
DCI format 2A	Used for PDSCH scheduling of terminals configured in an open-loop spatial multiplexing mode
DCI format 3	Used to transmit TPC commands of PUCCH and PUSCH with 2-bit power adjustments
DCI format 3A	Used to transmit TPC commands of PUCCH and PUSCH with 1-bit power adjustment

The control region for the PDCCH is composed of logical CCE columns that are a plurality of CCEs. The CCE column is a collection of all CCEs constituting the control region in one subframe. The CCE includes a plurality of resource element groups (REGs). For example, the CCE may include 9 REGs. The REG includes a plurality of resource elements. For example, one REG may include four resource elements.

The PDCCH is transmitted on an aggregation of one or several consecutive control channel elements (CCEs). The format of the PDCCH and the number of bits of the PDCCH are determined according to the number of CCEs constituting the CCE group. The number of CCEs used for PDCCH transmission is called a CCE aggregation level. {1, 2, 4, 8} CCEs may be used to configure one PDCCH, and each element of {1, 2, 4, 8} is called a CCE aggregation level.

6 shows a structure of an uplink subframe. This may be referred to Section 5.4 of 3GPP TS 36.211 V8.5.0 (2008-12) "Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation (Release 8)".

Referring to FIG. 6, an uplink subframe may be divided into a control region to which a PUCCH (Physical Uplink Control Channel) is allocated and a data region to which a PUSCH (Physical Uplink Shared Channel) is allocated.

The PUCCH for one UE is allocated to a resource block (RB) pair (51, 52) in a subframe, and the RBs 51 and 52 belonging to the RB pair occupy different subcarriers in each of two slots. do. This is said that the RB pair allocated to the PUCCH is frequency hopping at the slot boundary.

According to 3GPP TS 36.211 V8.5.0 (2008-12), PUCCH supports multiple formats. A PUCCH having a different number of bits per subframe may be used according to a modulation scheme dependent on the PUCCH format.

Table 2 below shows an example of a modulation scheme and the number of bits per subframe according to the PUCCH format.

PUCCH Format	Modulation Scheme	Number of Bits per subframe
One	N / A	N / A
1a	BPSK	One
1b		QPSK	2
2	QPSK	20
2a	QPSK + BPSK	21
2b	QPSK + BPSK	22

PUCCH format 1 is used for transmission of SR (Scheduling Request), PUCCH format 1a / 1b is used for transmission of ACK / NACK signal for HARQ, PUCCH format 2 is used for transmission of CQI, PUCCH format 2a / 2b is used for CQI and Used for simultaneous transmission of ACK / NACK signals. PUCCH format 1a / 1b is used when transmitting only the ACK / NACK signal in the subframe, and PUCCH format 1 is used when the SR is transmitted alone. When transmitting SR and ACK / NACK at the same time, PUCCH format 1 is used, and an ACK / NACK signal is modulated and transmitted on a resource allocated to the SR.

All PUCCH formats use a cyclic shift (CS) of the sequence in each OFDM symbol. The cyclically shifted sequence is generated by cyclically shifting a base sequence by a specific cyclic shift amount. The specific CS amount is indicated by the cyclic shift index (CS index).

7 shows transmission and reception of data in 3GPP LTE.

7A shows transmission of uplink data. The UE monitors the PDCCH in a downlink subframe and receives an uplink resource allocation (or an uplink grant) on the PDCCH 101. The terminal transmits an uplink transport block on the PUSCH 102 configured based on the uplink resource allocation.

7B shows reception of downlink data. The terminal receives the downlink transport block on the PDSCH 152 indicated by the PDCCH 151. The UE monitors the PDCCH in a downlink subframe and receives a downlink resource allocation (or downlink grant) on the PDCCH 151. The terminal receives a downlink data packet on the PDSCH 152 indicated by the downlink resource allocation.

8 is an exemplary diagram illustrating monitoring of a PDCCH. This may be referred to in section 9 of 3GPP TS 36.213 V8.5.0 (2008-12). In 3GPP LTE, blind decoding is used to detect the PDCCH. Blind decoding is a method of demasking a desired identifier in a CRC of a received PDCCH (which is called a PDCCH candidate), and checking a CRC error to determine whether the corresponding PDCCH is its control channel. The UE does not know where its PDCCH is transmitted using which CCE aggregation level or DCI format at which position in the control region.

The base station determines the PDCCH format according to the DCI to be sent to the terminal, attaches a cyclic redundancy check (CRC) to the DCI, and unique identifier according to the owner or purpose of the PDCCH (this is called a Radio Network Temporary Identifier) Mask to the CRC.

If the PDCCH is for a specific terminal, a unique identifier of the terminal, for example, a C-RNTI (Cell-RNTI) may be masked to the CRC. Alternatively, if the PDCCH is for a paging message, a paging indication identifier, for example, P-RNTI (P-RNTI), may be masked to the CRC. If it is a PDCCH for system information, a system information identifier and a system information-RNTI (SI-RNTI) may be masked to the CRC. A random access-RNTI (RA-RNTI) may be masked to the CRC to indicate a random access response that is a response to the transmission of the random access preamble of the UE. TPC-RNTI may be masked to the CRC to indicate a transmit power control (TPC) command for a plurality of terminals.

A plurality of PDCCHs may be transmitted in one subframe. The UE monitors the plurality of PDCCHs in every subframe. In this case, the monitoring means that the UE attempts to decode the PDCCH according to the monitored PDCCH format.

In 3GPP LTE, a search space is used to reduce the burden of blind decoding. The search space may be referred to as a monitoring set of the CCE for the PDCCH. The UE monitors the PDCCH in the corresponding search space.

The search space is divided into a common search space and a UE-specific search space. The common search space is a space for searching for a PDCCH having common control information. The common search space includes 16 CCEs up to CCE indexes 0 to 15 and supports a PDCCH having a CCE aggregation level of {4, 8}. However, PDCCHs (DCI formats 0 and 1A) carrying UE specific information may also be transmitted in the common search space. The UE-specific search space supports a PDCCH having a CCE aggregation level of {1, 2, 4, 8}.

Table 3 below shows the number of PDCCH candidates monitored by the UE.

Search Space Type	Aggregation level L	Size [In CCEs]	Number of PDCCH candidates	DCI formats
UE-specific		One	6	6	0, 1, 1A, 1B, 1D, 2, 2A
	2	12	6
	4	8	2
	8	16	2
Common	4	16	4	0, 1A, 1C, 3 / 3A
	8	16	2

The size of the search space is determined by Table 3, and the starting point of the search space is defined differently from the common search space and the terminal specific search space. The starting point of the common search space is fixed irrespective of the subframe, but the starting point of the UE-specific search space is for each subframe according to the terminal identifier (eg, C-RNTI), the CCE aggregation level and / or the slot number in the radio frame. Can vary. When the start point of the terminal specific search space is in the common search space, the terminal specific search space and the common search space may overlap.

Now, a multiple carrier system will be described.

The 3GPP LTE system supports a case where the downlink bandwidth and the uplink bandwidth are set differently, but this assumes one component carrier (CC). This means that 3GPP LTE is supported only when the bandwidth of the downlink and the bandwidth of the uplink are the same or different in the situation where one CC is defined for the downlink and the uplink, respectively. For example, the 3GPP LTE system supports up to 20MHz, and the uplink bandwidth and the downlink bandwidth may be different, but only one CC is supported for the uplink and the downlink.

Spectrum aggregation (or bandwidth aggregation, also known as carrier aggregation) supports a plurality of CCs. Spectral aggregation is introduced to support increased throughput, to prevent cost increases due to the introduction of wideband radio frequency (RF) devices, and to ensure compatibility with existing systems. For example, if five CCs are allocated as granularity in a carrier unit having a 20 MHz bandwidth, a bandwidth of up to 100 MHz may be supported.

The size of the CC (or bandwidth of the CC) may be different. For example, assuming that 5 CCs are used to configure a 70 MHz band, a 5 MHz carrier (CC # 0) + 20 MHz carrier (CC # 1) + 20 MHz carrier (CC # 2) + 20 MHz carrier (CC # 3) It may also be configured as a + 5MHz carrier (CC # 4).

A case in which the number of downlink CCs and the number of uplink CCs are the same or the downlink bandwidth and the uplink bandwidth are the same is called symmetric aggregation. A case where the number of downlink CCs and the number of uplink CCs are different or when the downlink bandwidth and the uplink bandwidth are different is called asymmetric aggregation.

In the multi-carrier system, at least one medium access control (MAC) entity may manage and operate at least one CC to transmit and receive at least one CC. The MAC entity has a higher layer of the physical layer (PHY). For example, the MAC entity may be implemented with a MAC layer and / or a higher layer thereof.

9 shows an example of a transmitter and a receiver in which multiple MACs operate multiple carriers. (A) is the transmitter and (B) is the receiver. A plurality of MACs (MAC 0, ..., MAC n-1) are mapped 1: 1 to the plurality of physical layers (PHY 0, ..., PHY n-1).

Each CC has an independent physical layer and an independent MAC layer. The MAC layer of the transmitter performs MAC protocol data unit (PDU) generation and L1 / L2 scheduling for the MAC / RLC (Radio Link Control) layer. The MAC PDU generated in the MAC layer of the transmitter is converted into a transport block through a transport channel and then mapped to a physical layer.

10 shows an example of a transmitter and a receiver in which one MAC operates multiple carriers. (A) is the transmitter and (B) is the receiver. One physical layer (PHY) corresponds to one CC, and a plurality of physical layers (PHY 0, ..., PHY n-1) are operated by one MAC. The mapping between the MAC and the plurality of physical layers (PHY 0, ..., PHY n-1) may be dynamic or static.

The MAC PDU generated at the MAC layer of the transmitter is converted into a transport block through a transport channel, decomposed, and then mapped to a physical layer.

PDSCH may be allocated to each CC. The PDCCH for indicating each PDSCH may be transmitted through the same CC or different CCs. The PDCCH may be allocated for each PDSCH or for each CC, which is referred to as a partition coded PDCCH. Alternatively, PDCCHs for a plurality of PDSCHs may be allocated, which is called a joint coded PDCCH.

In the following, the proposed invention can be applied to the division coded PDCCH and the joint coded PDCCH, and the PDCCH is referred to as a division coded PDCCH unless otherwise specified.

In order to support the multi-carrier, CCs that are subject to measurement may be allocated uniquely for each terminal. This measurement target CC may be allocated to measurement for normal transmission and reception of the physical channel after the RRC connection is established, and may be allocated for measurement for cell selection / cell reselection.

When the CC allocation information is controlled in the L3 RRM (radio resource management), the CC allocation information may be transmitted through UE-specific RRC signaling or may be transmitted through L1 / L2 control signaling. L1 / L2 control signaling refers to signaling through a PDCCH or other dedicated physical control channel.

When the CC allocation information is controlled by the packet scheduler, the CC allocation information may be transmitted through L1 / L2 control signaling.

11 shows an example of a multi-carrier system. The number of DL CCs is N and the number of UL CCs is M. N and M are natural numbers and at least one may be equal to or greater than two.

The UE may establish an RRC connection based on one arbitrary CC through an initial access process. The initial access process includes a cell search process, system information acquisition, and a random access process. After establishing an initial access procedure or an RRC connection, the UE may receive multi-carrier configuration information from a base station (or a relay station, hereinafter, referred to as the following).

The multi-carrier configuration information is information for multi-carrier operation between the base station and the terminal (or RN) and includes information on CCs supported by the terminal and / or the base station. The multi-carrier configuration information may include information about CCs allocated to the terminal.

The multi-carrier configuration information may be transmitted through UE-specific signaling. The UE may acquire multi-carrier configuration information through dedicated signaling such as an RRC message or a PDCCH.

When the CC configuration for the UEs is configured in units of a cell, a base station, or a cell cluster, it may be transmitted through a cell-specific RRC message or PDCCH signaling that is cell-specific and common to the UE.

Multi-carrier configuration information may be obtained through system information during the initial access process. Or, it may be obtained through system information or cell-specific RRC signaling received after the RRC connection is established.

12 shows an example of operation of a multi-carrier. For a terminal supporting multiple carriers, a CC configuration for a PDDCH used for PDSCH reception or PUSCH transmission needs to be defined. For this purpose, a DL-UL CC linkage may be defined.

The DL-UL CC linkage refers to a mapping relationship between a DL CC on which a PDCCH carrying an UL grant is transmitted and an UL CC using the UL grant. Alternatively, the DL-UL CC linkage may be a mapping relationship between a DL CC (or UL CC) in which data for HARQ is transmitted and a UL CC (or DL CC) in which a HARQ ACK / NACK signal is transmitted. The DL-UL CC linkage information may inform the UE by the base station as part of a higher layer message or system information such as an RRC message. The linkage between the DL CC and the UL CC may be fixed but may be changed between cells / terminals.

The UE receives the PDSCH 702 through the DL CC #i to which the PDCCH 701 carrying the DL grant is transmitted. Similarly, the UE transmits the PUSCH 712 through the UL CC #e linked with the DL CC #i to which the PDCCH 711 carrying the UL grant is transmitted.

The UE receives the PDSCH 742 through DL CC #j in which the PDCCH 741 carrying the DL grant is transmitted. Likewise, the UE transmits the PUSCH 752 through the UL CC #f linked with the DL CC #j in which the PDCCH 751 carrying the UL grant is transmitted.

12 assumes a situation in which the number of DL CCs and the number of UL CCs are symmetrically configured, but may be applied to an asymmetrical case.

In the example of FIG. 12, PDCCH-PDSCH pairs are transmitted on the same CC. When overriding the DL-UL CC linkage, when the transmission power of a specific DL CC or UL CC is low, when the bandwidth of a specific DL CC or UL CC is small, to reduce the PDCCH blind decoding overhead, The corresponding PDSCH may be transmitted through different CCs. In addition, the PUSCH corresponding to the PDCCH may be transmitted to another UL CC other than the linked UL CC. This is called cross carrier scheduling. Cross-carrier scheduling may include soft silencing that significantly lowers transmission power of a specific DL CC / UL CC or hard silencing technology that turns off power of a specific DL CC / UL CC.

Cross carrier scheduling can be implemented in two ways. The first is to configure a DL CC transmitting a corresponding DL grant or a PDCCH for a UL grant for a PDSCH transmission on one or more DL CCs or a PUSCH transmission on one or more UL CCs for an arbitrary UE or cell. . This can be set via a semi-static message such as an RRC message or system information. The second is to indicate the DL CC or UL CC through which the associated PDSCH or PUSCH is transmitted through DCI on the scheduling PDCCH.

13 shows an example of cross carrier scheduling.

PDCCH 801 carries a UL grant for PUSCH 802 of UL CC #e linked to DL CC #i. The PDCCH 811 carries a DL grant for the PDSCH 812 of the DL CC #i. Accordingly, cross carrier scheduling is not applied to the PDCCH 801 and the PDCCH 811.

PDCCH 821 of DL CC #i carries a UL grant for PUSCH 822 of UL CC #f. The PDCCH 821 may be referred to as a UL grant PDCCH. The PDCCH 831 of the DL CC #i carries the DL grant for the PDSCH 832 of the DL CC #j. The PDCCH 831 may be referred to as a DL grant PDCCH. The PDCCH 821 and the PDCCH 831 are cross carrier scheduling applied.

When cross carrier scheduling is applied, DL grants and / or UL grants of several DL / UL CCs are transmitted in the control region of a specific DL CC. When the UE blindly decodes the PDCCH in the corresponding DL CC, after performing CRC demasking using the UE-specific or carrier-specific C-RNTI, a corresponding DCI for a PDSCH or PUSCH of a certain DL CC or UL CC You need to know if it is control information. Information indicating which CC the DCI on the PDCCH is for is referred to as a carrier indicator (CI) or a carrier indicator field (CIF). The CIF may be included in an explicit DCI format, included in control information via another encoding, or signaled implicitly.

Hereinafter, a configuration method and a signaling method according to the application of cross carrier scheduling according to an embodiment of the present invention will be described.

CIF Definition and Bit Size

CIF is information indicating which DL / UL CC the UL / DL grant on the PDCCH is. CIF may be represented as a CC index (DL CC index or UL CC index). In this case, the CC index may be represented in various forms.

In the first embodiment, the CC index may be given as the CC index for the absolute value in the frequency domain. The CC index may be given as an index of absolute values for a series of bands specified in the IMT band or the 3GPP standard. For example, if the number of bands specified in the IMT band or the 3GPP standard is N, the total number of CC indexes is N. The bit size of CIF may be given as ceil (log ₂ N). Here, ceil (x) represents a minimum integer among integers greater than or equal to x.

If there are N1 DL CCs, there may be N2 UL CCs. N1 and N2 may be the same value or different values. The size of the CIF for the DL CC may be ceil (log ₂ N1), and the size of the CIF for the UL CC may be ceil (log ₂ N2). The CIF for the DL CC may be included in the DL Grant PDCCH, and the CIF for the UL CC may be included in the UL Grant PDCCH.

In a second embodiment, the CC index may be determined based on the logical order of the DL CCs and / or UL CCs. For example, when the number of DL CCs or UL CCs configured by the base station is M (a natural number of 1 or more), the bit size of the CIF may be given as ceil (log ₂ M).

If the index is determined based on the logical order, the bit size may be reduced compared to the case where the index is expressed as an absolute value index for the band of the DL CC or the UL CC. For example, if the index of the absolute value for the band of the DL CC is given by {1, 3, 6, 7} N is required 3 bits when represented as the index of the absolute value, but the index is based on the logical order In this case, M may be represented by 2 bits.

In order to reduce the blind decoding overhead (or to reduce the complexity of the implementation or to prevent ambiguity from occurring), the CIF may have a predetermined bit size. For example, when the larger value of the maximum number of DL CCs that can be configured by a cell or a base station and the maximum number of UL CCs that can be configured by a cell is A, CIF is a bit of ceil (log ₂ A). It may have a size.

When the DL CC and the UL CC have different numbers of indexes (for example, M1 and M2), the CIF for the DL CC is ceil (log ₂ M1), and the CIF for the UL CC is ceil (log ₂ M2). It can have a bit size as well. To reduce blind decoding overhead, the CIF may have a predetermined bit size. In this case, the bit size of the CIF for the DL CC and the bit size of the CIF for the UL CC may be designated the same or different.

In a third embodiment, an index of a CIF may be defined based on a logical order of DL CCs and / or UL CCs that are specifically set by a cell or a base station by a terminal / cell / base station / cell cluster.

The bit size of the CIF is ceil (log ₂ Q) when the number of DL CCs or UL CCs that are specifically set by the base station to UE / cell / base station / cell cluster is Q. Alternatively, the terminal may have a bit size of a predetermined fixed value in order to prevent overhead / ambiguity when performing blind decoding. The fixed value is, for example, the largest number of DL CCs or UL CCs that can be configured by the UE to the maximum among the number of DL CCs or UL CCs specifically set by the BS / cell / base station / cell cluster. If the value is given as A, it can be given as ceil (log ₂ A). This value may be used in common for the DL grant PDCCH and the UL grant PDCCH.

As for the bit size of the CIF, the number of DL CCs or UL CCs that are specifically set by a base station to a terminal / cell / base station / cell cluster may have different values Q1 and Q2. In this case, the bit size of each CIF transmitted for cross-carrier scheduling on the DL grant PDCCH and the UL grant PDCCH is determined by ceil (log ₂ Q1), ceil ( log ₂ Q2). To reduce blind decoding overhead, the CIF may have a predetermined bit size. In this case, the bit size of the CIF for the DL CC and the bit size of the CIF for the UL CC may be designated the same or different.

In the above embodiments, when the index of the IMT band or the bands specified in the 3GPP standard is given as an absolute value (w, x, y, z) and a relationship of w <x <y <z is established, DL CC # w , DL CC # x, DL CC # y, and DL CC # z may be four DL CCs configured by the transmitting station. In this case, the size of the absolute value index is specified in a logical order so that DL CC # w is the DC CC index # 0, DL CC # x is the DC CC index # 1, DL CC # y is the DC CC index # 2, and DL CC # z can be specified as DC CC index # 3.

In the above-described third embodiment, a DL CC linked to one DL CC and the DL CC before any UE establishes an RRC connection through an initial access procedure or handover or cell selection / reselection to an arbitrary cell. CC may be determined according to a predefined cell common or cell specific link relationship), and may be applied when a carrier is configured through signaling. In this process, the link relationship between the DL CC and the UL CC may be performed through the RRC signaling or the L1 / L2 control signaling specifically for the UE / cell / base station / cell cluster.

For example, it is assumed that when UE-specific CC assignment is made, the UE has S DL CCs allocated from the cell and the UL CCs allocated are T. In this case, the bit sizes of the CIF transmitted on the DL grant PDCCH and / or the UL grant PDCCH for the UE are ceil (log ₂ S) and ceil (log ₂ T), respectively. For example, when S = 4 and T = 2, the bit size of the CIF transmitted through the DL grant PDCCH may be 2 bits, and the bit size of the CIF transmitted on the UL grant PDCCH may be 1 bit. The bit size of the CIF may vary according to UE specific carrier assignment performed through RRC signaling or L1 / L2 PDCCH control signal signaling.

Alternatively, unlike the above-described method, the bit size of the CIF may be fixed according to a maximum value of the number of DL CCs and the number of UL CCs defined by UE specific capability. For example, when the maximum number of DL CCs configurable for the UE is 4, the bit size of the CIF transmitted on the DL grant PDCCH may be fixed to 2 bits. Alternatively, when the maximum number of DL CCs configurable to the UE is 5, the bit size of the CIF transmitted on the DL grant PDCCH may be fixed to 3 bits. Similarly, when the maximum number of UL CCs configurable to the UE is 3 or 4, the bit size of the CIF included in the UL grant PDCCH and transmitted may be fixed to 2 bits, and when the maximum number of UL CCs configurable to the UE is 2, The bit size of the CIF included in the UL grant PDCCH and transmitted may be fixed to 1 bit. In the above example, the bit size of the CIF included in the UL grant PDCCH and the bit size of the CIF included in the DL grant PDCCH may be fixed to be the same as the bit size having a larger value.

Alternatively, the bit size of the CIF transmitted by being included in the DL grant PDCCH or the UL grant PDCCH may be notified through RRC signaling or L1 / L2 PDCCH control signal signaling.

The bit size of the above-described CIF is the index value of the DL CC or the number of DL CCs or the index value of the UL CC that the transmitting station (cell or base station or relay station) sets to the receiving station (terminal or relay station) specifically for the terminal / relay station / cell. Or based on the number of UL CCs. But this is not a limitation. For example, a method of sub grouping in the UE DL CC set or the UE UL CC set may be applied by a predefined rule or an explicit method through an implicit or higher layer signal. In this case, the transmitting station may inform the receiving station of information on the subgroup to which the carrier receives the scheduling PDCCH. Then, the receiving station, for example, the UE can know which subgroup to belong to within the UE DL CC set or the UE UL CC set to receive the scheduling PDCCH. Accordingly, the bit size of the CIF transmitted in the DL grant PDCCH or the UL grant PDCCH included in the scheduling PDCCH is based on the number of DL CCs in the subgroup, the maximum index value of the DL CCs, the number of UL CCs, or the maximum index value of the UL CCs. Can be determined. If the number or maximum index value of the DL CCs in the subgroup is X, the bit size of the CIF transmitted on the DL grant PDCCH may be set to ceil (log ₂ X).

When the index of the CIF uses the logical index of the DL / UL CC, the following method may be considered.

First, UE-specific UE DL CC set is defined for any terminal, but UE UL CC set is not defined. The bit size of the CIF included in the UL grant PDCCH may be set to ceil (log ₂ M2) based on the number of UL CCs configured by the transmitting station (the same as the cell, the base station, or the relay station).

On the contrary, if a UE-specific UE UL CC set is defined for a certain UE but the UE DL CC set is not defined, the bit size of the CIF included in the DL grant PDCCH is based on the number of DL CCs configured by the transmitting station. It can be set to ceil (log ₂ M1).

If neither UE-specific UE DL CC set nor UE UL CC set is defined for any UE, the bit size of each CIF transmitted for cross-carrier scheduling on the DL grant PDCCH and the UL grant PDCCH is configured by the transmitting station. According to the number of DL CC, UL CC M1, M2 may be defined as ceil (log ₂ M1), ceil (log ₂ M2), respectively.

Second, the transmitting station (cell or base station or relay station) may attempt to change the UE DL CC set and / or the UE UL CC set already set in the terminal based on a specific time point. That is, the UE DL CC set and / or the UE UL CC set already set in the terminal may be changed to another UE DL CC set and / or the UE UL CC set. As such, when the UE DL CC set and / or the UE UL CC set is dynamically changed, the bit size of each CIF transmitted for cross-carrier scheduling on the DL grant PDCCH and the UL grant PDCCH is the size of the DL CC configured by the transmitting station. It may be defined as ceil (log ₂ M1) and ceil (log ₂ M2), respectively, according to the number and the number M1 and M2 of the UL CC.

Third, assume a case where a transmitting station (cell or base station or relay station) sets a UE-specific DL CC set and / or a UE UL CC set. Any terminal may perform an initial access procedure based on one CC before receiving configuration information about the UE DL CC set and / or the UE UL CC set from the transmitting station. In this case, the UE blindly decodes the PDCCH through one DL CC initially set or detected. In this case, the transmitting station may include a CIF on the DCI format of the DL grant PDCCH or UL grant PDCCH included in the one DL CC. At this time, the bit size of the CIF may be defined as ceil (log ₂ M1) and ceil (log ₂ M2), respectively, depending on the number M1 of DL CCs and / or the number M2 of UL CCs configured by the transmitting station.

Fourth, when a transmitting station (cell or base station or relay station) configures UE-specific DL CC set and / or UE UL CC set, UE may perform a handover from the serving cell to the target cell. i) UE receiving configuration information of UE DL CC set and / or UE UL CC set of target cell through handover command of serving cell, ii) DL configured by target cell through handover command of serving cell The number of CCs and / or UL CCs and the indexes of DL CCs and / or UL CCs may be signaled. After the handover process is terminated, the terminal receives configuration information on the UE-specific UE DL CC set and / or the UE UL CC set from the target cell. In this case, the UE may blind decode the PDCCH through one DL CC designated or configured through a handover command before receiving the configuration information. In this case, the CDC for the cross carrier scheduling may be included in the PDCCH. At this time, the bit size of the CIF may be defined as ceil (log ₂ M1) and ceil (log ₂ M2), respectively, depending on the number M1 of DL CCs and / or the number M2 of UL CCs configured by the transmitting station.

Cross carrier scheduling setting method and related signaling method

Cross carrier scheduling may be always applied based on a DL CC, a UL CC configuration of a transmitting station (cell or base station), or a blind decoding overhead of a receiving station (eg, a terminal).

Alternatively, the basic carrier scheduling of FIG. 12 and the cross carrier scheduling of FIG. 13 may be selectively applied over time by applying a technique such as soft / hard carrier silencing to a time varying scheme. It may be informed through UE-specific or cell-specific or RS-specific RRC signaling about whether the basic carrier scheduling and cross-carrier scheduling is applied, and, in some cases, UE-specific or cell-specific or RS-specific L1 / L2. It may be informed through PDCCH control signal signaling. Signaling methods for information indicating whether to perform cross carrier scheduling that indicates whether to apply basic carrier scheduling or cross carrier scheduling can be largely classified into explicit signaling and implicit signaling.

First, explicit signaling is UE / cell specific RRC signaling or UE / cell specific L1 / L2 PDCCH for applying cross-carrier scheduling and basic carrier scheduling uniquely for each transmission station (cell or base station or relay station) unit or terminal. In the signaling method described above, the timing at which the basic carrier scheduling or the cross carrier scheduling is applied is the N (> 1, or 0) subframe in the DL subframe in which the RRC signal or the PDCCH control signal is received. It may be applied from a subsequent subframe. N may be a predefined value. For example, when the transmitting station transmits a control signal that cross carrier scheduling is applied in subframe #i, it may start to apply cross carrier scheduling from subframe # (i + N). In addition, the UE that receives the control signal that cross carrier scheduling is applied in subframe #i may recognize that cross carrier scheduling is applied from subframe # (i + N) and perform blind decoding according to cross carrier scheduling. . That is, from subframe # (i + N), blind decoding may be performed on the assumption that CIF is included in the PDCCH.

In this case, the 1-bit mode indicator may be included in the RRC parameter included in the RRC signal. The 1-bit mode indicator may inform the receiving station (terminal or relay station) of the default carrier scheduling (eg, when '0') or cross carrier scheduling (eg, when '1') according to the value. Alternatively, the RRC signal may include a separate field in addition to the aforementioned 1 bit mode indicator. For example, index indicators of one or more DL CCs to which cross-carrier scheduling is applied and / or index indicators of UL CCs, index indicators of DL CCs to which scheduling PDCCHs are transmitted, are included in DL grant PDCCHs and / or UL grant PDCCHs. And a bit size field of the CIF.

Upon receiving the RRC signaling including the above-described RRC parameters, the UE may know the bit size of the CIF included in the DL grant PDCCH during PDCCH blind decoding, and in some cases, the bit size of the CIF included in the UL grant PDCCH. have.

Next, implicit signaling is that the UE determines the cross carrier scheduling without additional signaling. When the information on the PDCCH monitoring set is separately transmitted through RRC signaling or the L1 / L2 PDCCH control signal signaling, the UE may determine information on the separately transmitted PDCCH monitoring set and the DL CC on the UE DL CC set configured in the basic carrier scheduling. Compare counts or index configurations. As a result, when the information on the separate PDCCH monitoring set and the number or index configuration of the DL CCs on the UE DL CC set configured in the basic carrier scheduling are the same, it is recognized that the basic carrier scheduling is applied. On the other hand, if the information on the separate PDCCH monitoring set and the number or index configuration of the DL CCs set in the basic carrier scheduling is different (for example, the number of DL CCs set in the information on the PDCCH monitoring set is UE-specific carrier). It is recognized that cross-carrier scheduling is applied when the allocation is smaller than the number of DL CCs or when the index configuration is different.

For example, when the transmitting station transmits information on a PDCCH monitoring set different from the DL CC set allocated to the UE in subframe #i, cross carrier scheduling may be started from subframe # (i + N). In addition, the UE that has received information on the DL CC set allocated to itself in subframe #i and the PDCCH monitoring set different from the UE recognizes that cross-carrier scheduling is applied from subframe # (i + N) and blinds according to cross-carrier scheduling. Decoding can be performed. That is, from subframe # (i + N), blind decoding may be performed on the assumption that CIF is included in the PDCCH.

In this case, the bit size of the CIF included in the DL grant PDCCH or the UL grant PDCCH is the number of DL CCs set on the UE-specific carrier assignment or DL CC set (which may be cell-specific or RS-specific in some cases) (S And / or the number (T) of UL CCs (ceil (log ₂ (S)), ceil (log ₂ (T))).

Alternatively, the bit size of the CIF included in the DL grant PDCCH or the UL grant PDCCH may be determined to be a fixed value. The bit size of the CIF may be determined according to the maximum number of DL CCs and / or the number of UL CCs that can be allocated to the terminal.

The PDCCH monitoring set may be explicitly signaled by being defined as an RRC parameter. In this case, the receiving station (terminal or relay station) may receive from the transmitting station (cell or base station or relay station) or cell-specifically in a receiving station specific (ie, terminal specific or relay station specific).

The PDCCH monitoring set may be transmitted by L1 / L2 PDCCH control signal signaling. Alternatively, the PDCCH monitoring set may be set implicitly with a combination of at least two or more different types of parameters among RRC parameters. For example, it may be set to a combination of an indicator for the UE DL CC set included in the RRC parameter, an indicator indicating the index of the PDCCH transmission DL CC in the UE DL CC set. Alternatively, a combination of an indicator indicating an index of a DL DL in which UE-specific PDCCH transmission is not performed in the UE DL CC set and the UE DL CC set may be set.

The PDCCH monitoring set is a set of PDCCHs associated with downlink PDSCH transmissions (which may be referred to as a PDCCH monitoring set for DL PDSCH transmissions) and a set of PDCCHs associated with uplink PUSCH transmissions (this is a PDCCH for UL PUSCH transmissions). Can be defined as a monitoring set). Then, the CIF included in the DL grant PDCCH is set based on the relationship between the PDCCH monitoring set for the DL PDSCH transmission and the UE DL CC set, and the CIF included in the UL grant PDCCH is the PDCCH monitoring set for the UL PUSCH transmission and the UE UL CC set. Can be set based on the relationship of

PHICH transmission method when cross carrier scheduling is applied / released

The PHICH carries an ACK / NACK signal for uplink HARQ.

14 shows uplink synchronous HARQ in 3GPP LTE.

The terminal receives an initial UL grant on the PDCCH 910 in the nth subframe from the base station. The UE transmits an uplink transport block on the PUSCH 920 using the UL grant in the n + 4th subframe.

The base station sends an ACK / NACK signal for the uplink transport block on the PHICH 931 in the n + 8th subframe. An ACK / NACK signal indicates an acknowledgment for the uplink transport block, an ACK signal indicates a reception success, and a NACK signal indicates a reception failure. When the ACK / NACK signal is a NACK signal, the base station may send a retransmission UL grant on the PDCCH 932 or may not send a separate UL grant.

The terminal receiving the NACK signal transmits a retransmission block on the PUSCH 940 in the n + 12th subframe. For transmission of the retransmission block, the UE uses the received retransmission UL grant when receiving the retransmission UL grant on the PDCCH 932 and uses the initial UL grant when the retransmission UL grant is not received.

After initial transmission in the n + 4th subframe, since retransmission is performed in the n + 12th subframe, synchronous HARQ is performed using 8 subframes as the HARQ period.

In a multi-carrier system, a PHICH carrying an ACK / NACK signal for PUSCH transmission may be transmitted through a DL CC on which an UL grant PDCCH for the PUSCH transmission is transmitted.

However, when cross carrier scheduling is applied, a PHICH may be transmitted through a DL CC other than the DL CC on which the UL grant PDCCH for PUSCH transmission is transmitted. That is, a situation may occur in which a PDCCH monitoring set of a receiving station (terminal or relay station) on the premise of cross carrier scheduling and a DL CC to which a PHICH is transmitted are set differently.

That is, in case of informing the UE of the cross carrier scheduling configuration by the above explicit signaling or implicit signaling, the UE starts after N subframes in the subframe in which the explicit or implicit signal indicating that the cross carrier scheduling is configured is received. Cross carrier scheduling configuration may be applied. In this case, if the PHICH is transmitted to the DL CC transmitting the UL grant for the PUSCH transmission before the cross carrier scheduling configuration is applied, the PDCCH monitoring after the cross carrier scheduling configuration is maintained. The PHICH may be transmitted through a DL CC not included in the set. For example, the UE may transmit a PUSCH through UL CC # 1, and may transmit a PHICH in DL CC # 1 in which the base station transmits a UL grant for the PUSCH transmission of the UL CC # 1 according to basic carrier scheduling. At this time, cross-carrier scheduling may be applied between the PUSCH transmission time point and the PHICH transmission time point to configure a PDCCH monitoring set. If DL CC # 1 is not included in the PDCCH monitoring set, the UE may receive a PHICH through a DL CC different from the PDCCH monitoring set.

In order to solve this problem, a fundamentally applicable method is to define that PHICH transmission is performed in a DL CC transmitting the UL grant PDCCH for PUSCH transmission of the UE. This method may be changed if cross carrier scheduling is activated.

In the first embodiment, when the receiving station (terminal or relay station) receives the cross carrier scheduling configuration signal explicitly or implicitly, the DL CC receiving the UL grant PDCCH for the PUSCH transmitted before the cross carrier scheduling configuration is activated. May not receive the PHICH, and may receive the PHICH from the PDCCH monitoring set according to the cross-carrier scheduling configuration (if there are a plurality of DL CCs in the PDCCH monitoring set, a predetermined DL CC or a DL CC determined as an anchor DL CC). .

Alternatively, when cross carrier scheduling is applied to the UL CC transmitting the PUSCH, a DL CC transmitting the UL grant PDCCH is newly configured, and the UE receives the configuration information on the DL CC through RRC signaling or L1 / L2 control signaling. The terminal may receive a PHICH through the new DL CC. That is, the base station transmits the PHICH on a new DL CC transmitting the UL grant PDCCH. In this case, the PHICH resource configuration may be determined according to the PHICH resource configuration applied at the time of cross-carrier scheduling, or a separate RRC configuration or a special rule may be applied. The base station may set a PHICH DL CC according to a method that the terminal determines, and may set and transmit a PHICH group and channel resources.

In the second embodiment, when a UE-specific situation to which the UE's capability or cross-carrier scheduling is applicable is recognized by the UE, the method of transmitting the PHICH through the DL CC transmitting the UL grant PDCCH is not applied. (Or relay station) The PHICH may be transmitted over a specific or cell specific primary / anchor DL CC. The receiving station (terminal or relay station) and the transmitting station (base station) perform the reception and transmission process of PHICH according to the above-described method.

4. Recognition method of scheduling PDCCH transmission DL CC when cross carrier scheduling is applied

When cross carrier scheduling is applied, a plurality of DL CCs capable of transmitting a scheduling PDCCH (ie, a PDCCH carrying a UL grant or a DL grant) may be configured. It is necessary to define which DL CC of the plurality of DL CCs to transmit the DL grant PDCCH and the UL grant PDCCH.

In the first embodiment, the link relationship between the DL CC transmitting the scheduling PDCCH and the DL CC transmitting the PDSCH (or the UL CC transmitting the PUSCH) may be predetermined or implicitly determined.

The PDCCH-PDSCH link relationship between the DL CC transmitting the PDSCH and the DL CC transmitting the DL grant PDCCH and / or the PDCCH-PUSCH link relationship between the UL CC transmitting the PUSCH and the DL CC transmitting the UL grant PDCCH is determined according to a predetermined rule. Can be determined based on this. That is, PDCCH-PDSCH link relationship and / or PDCCH- based on a DL CC index / UL CC index, C-RNTI of a UE, a subframe index value, etc. to which cross carrier scheduling is applied according to a predetermined rule without an explicit signaling. PUSCH link relationship may be set.

For example, assume that the number of DL CCs capable of transmitting a scheduling carrier, that is, a DL grant PDCCH or a UL grant PDCCH, is A. In this case, a logical index of the DL CC, which is a scheduling carrier, may be given from # 0 to # (A-1). In this case, it is assumed that the carrier index of the DL CC to which the PDSCH can be transmitted except for the DL CCs is i. In addition, a DL CC capable of transmitting a scheduling PDCCH and a PUSCH transmission capable UL CC having no link are configured logically on a carrier allocation between DL CC / UL CC or an absolute index of a carrier for an IMT band or a band according to a 3GPP standard. Assume the carrier index is j. Under the assumption, the DL grant PDCCH for PDSCH transmission of DL CC #i may be transmitted through DL CC # (i% A) among the DL CC # 0 to DL CC # (A-1), and the UL CC The UL grant PDCCH for PUSCH transmission of #j may be transmitted through DL CC # (j% A) among the DL CC # 0 to DL CC # (A-1).

If the number of DL CCs capable of transmitting the DL grant PDCCH or the UL grant PDCCH is A, any one of them is represented by DL CC # k (any one of k = 0, 1, ..., A-1). Can be. At least one of DL CCs that do not transmit the DL CC # k and the scheduling PDCCH (that is, the DL grant PDCCH or the UL grant PDCCH) may be included and grouped.

In addition to the above-described grouping method, a method of designating a DL CC for transmitting a UL grant PDCCH for PUSCH transmission on a UL CC may be considered.

As a first example, the UL grant PDCCH transmission for the PUSCH transmission on the UL CC linked with the DL CC #k grouped with the DL CC #k and the DL CC grouped with the DL CC #k, without separately establishing the relationship or grouping between the DL CC #k and the UL CC capable of PUSCH transmission DL CC Can be defined to run on #k.

As a second example, relationship setting or grouping between DL CC # k and a PUSCH transmittable UL CC may be separately performed. For example, assume that DL CC # k and UL CC # h are basically configured with a link, and the remaining UL CCs are not configured with a DL CC that transmits an UL grant PDCCH. In this case, if the DL CC transmitting the UL grant PDCCH and the UL CCs that are not linked with the link group are to be grouped (including UL CC # h), the PUSCH must be transmitted through the UL CC belonging to this group. The grant PDCCH may be transmitted to the UE through DL CC # k.

In the first and second examples described above, it is assumed that there is only one DL CC that transmits a scheduling PDCCH included in the DL CC group or a link is established in the UL CC group. For special reasons, for example, a plurality of DL CCs that transmit a scheduling PDCCH may be included in a DL CC group or associated with a UL CC group for PDCCH load balancing.

In a second embodiment, a method of establishing a relationship based on explicit signaling between a DL CC transmitting a scheduling PDCCH and a DL CC transmitting a PDSCH (or an UL CC transmitting a PUSCH) is proposed.

When cross carrier scheduling is applied to any terminal (or relay station), a DL CC that transmits a DL grant PDCCH for PDSCH transmission on any DL CC and / or a UL grant PDCCH for PUSCH transmission on any UL CC ( That is, any information on the DL CC transmitting the scheduling PDCCH may be RRC-signaled or UE-specific or cell-specific or RS-specific, or may be notified to the UE through L1 / L2 control signal signaling.

When the number of scheduling carriers (DL CCs) capable of transmitting scheduling PDCCHs (that is, DL grant PDCCHs and / or UL grant PDCCHs) is set to A, logical indexes of DL CCs, which are scheduling carriers, are set from # 0 to # (A-1). Can be given up to Any carrier of the scheduling carriers is indicated as DL CC # k (any one of k = 0, 1, ..., (A-1)). In this case, at least one or more DL CCs of the DL CCs not transmitting the scheduling PDCCH and the DL CC # k may be grouped into one group. In addition to the above-described grouping method, a method of designating a DL CC for transmitting a UL grant PDCCH for PUSCH transmission on a UL CC may be considered. The grouping method (the method of applying DL CCs and / or UL CCs configured by a cell or a base station or a relay station or set by an arbitrary terminal) is configured at a higher layer in a terminal-specific or cell-specific or relay station specific manner. This configuration information may be signaled to one or more terminals through RRC signaling or L1 / L2 PDCCH control signal signaling. The specific method of grouping is as follows.

As a first example, the UL grant PDCCH transmission for the PUSCH transmission on the UL CC linked with the DL CC #k grouped with the DL CC #k and the DL CC grouped with the DL CC #k, without separately establishing the relationship or grouping between the DL CC #k and the UL CC capable of PUSCH transmission DL CC Can be defined to run on #k. Grouping between DL CCs #k and DL CCs that do not transmit the scheduling PDCCH may be configured in an upper layer, and may be signaled by UE or cell-specific RRC signaling or L1 / L2 PDCCH control information. As a second example, relationship setting or grouping between DL CC # k and a PUSCH transmittable UL CC may be separately performed. For example, assume that DL CC # k and UL CC # h are basically configured with a link, and the remaining UL CCs are not configured with a DL CC that transmits an UL grant PDCCH. In this case, if the DL CC transmitting the UL grant PDCCH and the UL CCs that are not linked with the link group are to be grouped (including UL CC # h), the PUSCH must be transmitted through the UL CC belonging to this group. The grant PDCCH may be transmitted to the UE through DL CC # k. Grouping for DL CCs and / or UL CCs may be configured in an upper layer to be signaled with UE or cell specific RRC signaling or L1 / L2 PDCCH control information.

In the first and second examples described above, it is assumed that there is only one DL CC that transmits a scheduling PDCCH included in the DL CC group or a link is established in the UL CC group. For special reasons, for example, DL CCs that transmit scheduling PDCCHs for PDCCH load balancing may be included in a plurality of DL CC groups or associated with UL CC groups.

5. Application of CIF to Cross Carrier Scheduling

When cross carrier scheduling is applied and a plurality of DL CCs (scheduling DL CCs) for transmitting a scheduling PDCCH are configured, the UE performs blind decoding on the plurality of DL CCs. In this case, the operation of the UE may vary depending on whether CIF is included in the scheduling PDCCH of each scheduling DL CC.

In the first embodiment, when cross-carrier scheduling is applied, the base station may include CIF in the scheduling PDCCH of all scheduling DL CCs. The UE performs blind decoding on the assumption that all CIFs are included in blind decoding of all the scheduling DL CCs transmitting the scheduling PDCCH. That is, the transmitting station (cell or base station or relay station) transmits including CIF in all scheduling PDCCH transmissions regardless of whether cross-carrier scheduling is applied only to PDCCHs of some DL CCs. The receiving station (terminal or relay station) assumes that CIF is included on all DL CCs that monitor the scheduling PDCCH through blind decoding, and the bit size of the CIF is determined by the above-described method.

In the second embodiment, when cross-carrier scheduling is applied, the base station may transmit the CIF including only PDCCHs on some DL CCs or some PDCCHs among all DL CCs capable of transmitting PDCCHs. A DL CC transmitting a PDCCH to which cross carrier scheduling is applied may include a CIF in the scheduling PDCCH, and may be transmitted without a CIF in a DL CC not transmitting a PDCCH to which cross carrier scheduling is applied.

The UE may know whether cross-carrier scheduling is applied and a link relationship between the PDSCH transmission DL CC (or PUSCH transmission UL CC) and the scheduling PDCCH transmission DL CC by an explicit or implicit signaling method. When the UE blind decodes the scheduling PDCCH in all DL CCs monitoring the PDCCH through blind decoding, it may be assumed that the CIF is included with the aforementioned bit size on all PDCCH candidates of the specific DL CC to which cross-carrier scheduling is applied. have. On the other hand, it may be assumed that CIF is not included on all PDCCH candidates on a DL CC for which PDCCH transmission for cross carrier scheduling is not defined.

When the base station transmits the scheduling PDCCH to the UE through an arbitrary DL CC, DCI payload does not apply CIF to the scheduling PDCCH for the PDSCH transmitted to the DL CC or the PUSCH transmitted to the UL CC linked to the DL CC Configure payload When the UE performs blind decoding on the scheduling PDCCH in such a situation, the UE performs demodulation and decoding on the CCEs in the corresponding PDCCH search space on the assumption that the CIF is not included in the DCI payload.

If a DL CC capable of transmitting PDCCH (that is, a PDCCH monitoring set, an anchor DL CC, or a primary DL CC) is set to one in a UE-specific UE DL CC set, the PDCCH PDSCH transmission on the transmission DL CC may be defined that cross carrier scheduling is not applied. In addition, PUSCH transmission on a UL CC that is basically linked with a PDCCH transmission DL CC (receiving station (terminal or relay station) specific or a transmitting station (cell or base station or relay station) specific link) is not cross-carrier scheduling applied. It may be defined as PDCCH / PUSCH transmission. That is, it may be defined as a PDSCH / PUSCH transmission to which cross carrier scheduling is applied and a PDSCH / PUSCH transmission to which cross carrier scheduling is not applied from a UE or a cell perspective. In this case, the DCI format of the DL grant PDCCH or UL grant PDCCH to which cross-carrier scheduling is applied may include a CIF, and the CIF may not be included in the DCI format of the DL grant PDCCH or UL grant PDCCH to which cross-carrier scheduling is not applied. .

If the overhead is increased during blind decoding due to the difference in DCI format, in order to solve this problem, CIF is defined as information of DCI format or as separate L1 / L2 control information to separate from control information on other DCI formats. Encoding can be applied. Information encoded separately from the DCI format may be expressed as a cross carrier scheduling indicator for the PDCCH.

In order not to increase the total number of bits of the PDCCH, whether or not cross carrier scheduling is implicitly applied may be indicated by using a method of differently applying a scramble code. This may be done on the encoded bits of the DCI or by a method of differentiating the RNTI masked to the CRC before encoding of the DCI or masking with a scramble code in addition to the CRC. Alternatively, the modulation may be performed by differently giving a phase offset on a signal constellation upon modulation of DCI (this is the same as scrambling with a phase offset code for a modulation symbol). The above-described methods may be similarly applied even in a situation in which the number of DL CCs capable of transmitting PDCCH in a UE DL CC set is plural. In this case, one or more PDCCH / PDSCH transmissions and / or PDCCH / PUSCH transmissions to which cross carrier scheduling is not applied may be defined (the same as the number of DL CCs transmitting PDCCHs in the case of DL PDSCH transmissions).

6. How to send CIF details on PDCCH

The method of defining and including CIF in the scheduling PDCCH (DL grant PDCCH and / or UL grant PDCCH) will now be described in detail.

In the first embodiment, the CIF having the CIF bit size as described above is explicitly set as a separate field on the payload of the DCI format of the DL grant PDCCH or the DCI format of the UL grant PDCCH according to any transmission mode. Can be included. The size of the field may be determined according to the bit size of the CIF. In addition, the size of the field may be changed in units of subframes in the time domain according to a carrier configuration situation or whether a specific technology or configuration scheme is applied.

In the second embodiment, the CIF having the CIF bit size as described above may be explicitly encoded by an encoding method different from the control information of the DL grant PDCCH or the UL grant PDCCH. In some cases, the DCI format of the scheduling PDCCH may be configured with an encoded bit or modulation symbol level modulated by a separate modulation scheme. In addition, a CIF to which a separate encoding and / or modulation scheme is applied may be an additional CRC bit as a parity check code as a code for error detection. Through this, the UE can know the CIF in advance before decoding the DCI format of the scheduling PDCCH, thereby optimizing the PDSCH decoding latency.

In the third embodiment, the CIF may be implicitly included without introducing an additional process to the DCI format or the encoding / modulation scheme of the scheduling PDCCH. That is, the CIF may be expressed in an implicit manner without separately defining a field in a payload on a DCI format or designating a separate modulation symbol or encoded bit. For example, the status of the information indicated by the CIF may be identified by the masked C-RNTI. Alternatively, the state or bits of some fields already defined in the DCI format on the scheduling PDCCH may be used to indicate information indicated by the CIF. This method maintains backward compatibility because it does not change the payload of the DCI format.

The above-described embodiments can be applied in combination. At least one of the three embodiments may be applied to the state of the information represented by the CIF or some of the bits of the CIF.

7. Transmission of CFI (control format indicator) on PDCCH

When cross-carrier scheduling is applied to a receiving station (terminal or relay station), CFI may be determined by a method described below for DL CCs configured by a transmitting station (cell or base station or relay station) or DL CCs specifically assigned to a receiving station. Can transmit

The CFI may indicate the size of the control region in which the scheduling PDCCH is transmitted when scheduling PDSCH transmission by the CIF. Alternatively, the CIF may indicate the number (or index) of the OFDM symbol immediately preceding the OFDM symbol at which the data region in which the PDSCH is transmitted starts. If the CFI is the index of the OFDM symbol at which the data region starts, i, the CIF may indicate the OFDM symbol index i-1.

First, consider a case in which CFI values are commonly set in DL CCs. That is, the number of OFDM symbols (or the size of the control region) that can transmit the PDCCH in each DL CC is the same.

The UE may preferentially decode the PCFICH in which the CFI is transmitted in any DL CC that should perform the PDCCH blind decoding. That is, since the values of the CFI are the same in all DL CCs, the number of OFDM symbols in which the PDCCH of the DL CCs are transmitted can be determined by decoding the PCFICH in any DL CC regardless of whether cross carrier scheduling is applied or not.

Therefore, the base station does not need to define a field for transmitting the CFI value separately in the DCI format of the PDCCH dedicated to cross-carrier scheduling or the PDCCH delivered to the receiving station.

Next, consider a case where the CFI is independently configured for each DL CC.

In order to know the CFI value of each DL CC, the UE first decodes the CFI on the PCFICH in the DL CC to which the PDCCH which should be blindly decoded is transmitted. In addition, the UE additionally needs to obtain a CFI of the DL CC for the PDSCH to which cross-carrier scheduling is applied (this is called a second CFI). This is because it is necessary to know the size of the control region of another DL CC in order to decode the PDSCH transmitted on another DL CC to which cross carrier scheduling is applied. The following method is possible to obtain a second CFI.

In the first embodiment, the base station may transmit the PCFICH in the first OFDM symbol of the subframe regardless of whether cross carrier scheduling is applied or not. For example, assume that a scheduling PDCCH is transmitted in DL CC # 1 and indicates DL CC # 2 in a DL grant PDCCH of DL CC # 1. Then, the UE can know the size of the control region of the DL CC # 1 through the first CFI on the PCFICH of the DL CC # 1. In addition, the UE can know the size of the control region of the DL CC # 2 through the second CFI on the PCFICH of the DL CC # 2.

Upon receiving the PDCCH applied to the cross scheduling, the UE checks the size of the control region through the PCFICH of the DL CC before decoding the PDSCH in the DL CC indicated by the CIF.

In the second embodiment, the CFI of the DL CC on which the PDSCH is transmitted may be informed on the scheduling PDCCH of the DL CC to which cross carrier scheduling is applied. In this case, the UE does not need to first receive the PCFICH of the DL CC on which the PDSCH is transmitted. The base station may include a field indicating a second CFI for the PDSCH transmission DL CC in the DCI on the UE-cell specific scheduling PDCCH.

Only the UE to which the cross carrier scheduling is applied may include a field indicating a second CFI for the PDSCH transmission DL CC in the DCI of all DL grant PDCCHs. The UE to which the cross carrier scheduling is applied may know the second CFI through blind decoding.

For the UE to which the cross carrier scheduling is applied, the second CFI for the PDSCH transmission DL CC may be included in the DCI limited to DL grant PDCCHs to which the cross carrier scheduling is applied. The UE to which the cross carrier scheduling is applied may know the second CFI through blind decoding.

The DCI format including a field indicating a second CFI for the PDSCH transmission DL CC may be applied only to the DL grant PDCCH, and in some cases, may also be applied to the UL grant PDCCH. In this case, the second CFI may be included in the DCI on the UL grant PDCCH regardless of whether cross carrier scheduling is applied.

Independently of this, a field indicating a value of an uplink cell ID having a meaning of a physical cell ID or a logical cell ID as a reference associated with an uplink PUCCH or a PUSCH transmission configuration is a DCI. Can be included.

In the third embodiment, a dedicated physical control channel or DCI format indicating CFI may be defined separately. Regardless of whether cross-carrier scheduling is applied or not on the DL CC configured by the base station, the DL CC is limited to all DL CCs (primary DL CC or anchor DL CC) according to a specific criterion or all DL CCs configured to transmit PDCCH. All CFIs configured by the base station may be transmitted through a fixed CCE location in a PDCCH transmission region (on a cell common search space or a terminal specific search space) or an arbitrary CCE column that is variable in the common search space.

The dedicated physical control channel may be in the form of a general PDCCH defined through encoding and modulation of 3GPP LTE, or may be a method defined through encoding and modulation different from conventional PDCCH, such as PCFICH or PHICH of 3GPP LTE Release 8. .

In the fourth embodiment, the base station may inform the CFI for one or more DL CCs through terminal / cell specific signaling. CFIs for all DL CCs supported by the base station, CFIs for DL CCs supporting cross carrier scheduling, or CFIs for DL CCs supported by the UE may be informed. This information may be transmitted via RRC message, MAC message or L1 / L2 PDCCH control signaling.

In order to compensate for a case where a CFI reception error occurs, the above-described first to fourth embodiments may be used in combination, or any two or more embodiments may be used in combination.

In addition, the above embodiments may be applied or changed according to channel conditions of the terminals. While basically applying one of the first to fourth embodiments, if the decoding success of the PCFICH of the PDSCH transmission DL CC is guaranteed to a predetermined level or more, the second CFI may be determined using only the PCFICH. Whether to apply only PCFIC or whether to apply at least one of the first to fourth embodiments, the base station may inform the UE through RRC signaling, MAC signaling, or PDCCH.

The CFI transmission method on the PDCCH described above may be applied even when the meaning of CFI is different from the above example.

First, the meaning of CFI not only indicates the number of OFDM symbols capable of transmitting PDCCH in the corresponding DL CC, but also information common to other receiving stations (for example, information indicating a PHICH interval in the DL CC) or a receiver specific PDCCH configuration. The same may be applied to the case of common control information on the DL CC as in the case of having information.

Second, unique control information according to individual DL CCs such as the case in which the CFI indicates not only the number of OFDM symbols capable of transmitting PDCCH in a corresponding DL CC but also has PDCCH configuration information having a unique meaning to a specific receiver. This may also apply.

8. Meaning of DL-UL CC Linkage Setting

Regardless of whether cross carrier scheduling is applied or not, DL-UL CC linkage is set in the DL CC and UL CC configured by the transmitting station, in the transmission band / receive band separation of the system already defined on the IMT band, and in the upper layer. And may be defined according to a parameter signaled to a receiving station (terminal or relay station).

A cell / base station specific DL-UL CC linkage may be set by a configuration situation of DL CCs and UL CCs in a transmitting station and transmission band / receiving band separation of a system that is already defined on an IMT band.

UE-specific DL-UL CC linkage may be set implicitly or explicitly. In detail, the linkage is configured by implicit relation or control information explicitly signaled from the base station on the UE DL CC set and / or the UE UL CC set that are specifically configured for the terminal. Alternatively, some of cell-specific linkages may be used as DL-UL CC linkages.

9. Physical Channel Transmission CC Setup Associated with DL-UL CC Linkage

The physical channel of the DL CC and the physical channel of the UL CC may be configured based on cell / terminal specific DL-UL CC linkage.

The UL CC on which the uplink ACK / NACK is transmitted for the PDSCH transmitted on any DL CC may be set to the UL CC linked to the DL CC on which the DL grant PDCCH for the PDSCH or PDSCH is transmitted.

Alternatively, a DL CC in which downlink ACK / NACK is transmitted for a PUSCH transmitted through an arbitrary UL CC is a DL CC linked with an UL CC in which the PUSCH is transmitted or a DL CC for transmitting a UL grant PDCCH for the PUSCH. It may be set.

The above-described method may be applied between PDCCH-PDSCH or PDCCH-PUSCH based on CIF and may be used when cross carrier scheduling is applied or not applied.

When cross carrier scheduling is applied, a UL CC for transmitting an uplink ACK / NACK for a PDSCH transmitted on an arbitrary DL CC for a terminal to which carrier aggregation is applied may be configured in the following manner.

In the first embodiment, the UL CC through which the uplink ACK / NACK is transmitted for the PDSCH transmitted through any DL CC may be set to the UL CC linked with the DL CC through which the PDSCH is transmitted.

In the second embodiment, an UL CC through which an uplink ACK / NACK is transmitted for a PDSCH transmitted in an arbitrary DL CC (possibly PDCCH) is UL linked with a DL CC through which a DL grant PDCCH for the PDSCH is transmitted. It can be set as CC.

The DL-UL CC linkage may be cell / base station specific or terminal specific. In the second embodiment, when cross-carrier scheduling is applied, an uplink is performed through a UL CC linked with a DL CC configured for UE / cell specific to transmit a DL grant PDCCH for transmission of a PDSCH on one or more DL CCs. ACK / NACK may be transmitted. In this case, a UL CC transmitting uplink ACK / NACK may be regarded as a UL anchor CC or a UL primary CC.

The DL CC on which the downlink ACK / NACK (ie, PHICH) is transmitted for the PUSCH transmitted on any UL CC may be configured in the following manner.

In the first embodiment, the DL CC on which the downlink ACK / NACK (ie PHICH) is transmitted for the PUSCH transmitted on any UL CC may be set to the DL CC linked to the UL CC on which the PUSCH is transmitted. .

In the second embodiment, a DL CC on which a downlink ACK / NACK (ie, PHICH) is transmitted for a PUSCH transmitted on any UL CC may be set to a DL CC on which a UL grant PDCCH for the PUSCH is transmitted.

The DL-UL CC linkage may be cell / base station specific or terminal specific. In the second embodiment, when cross-carrier scheduling is applied, downlink ACK / NACK (PHICH) is performed through a DL CC configured for UE / cell specific to transmit UL grant PDCCH for PUSCH transmission on one or more UL CCs. It is assumed that the transmission. If the DL CCs transmitting the DL grant PDCCH and the UL grant PDCCH are set to be the same, this DL CC may be regarded as a DL anchor CC or a DL primary CC. Or in some cases, the characteristics of the DL CC may be defined to include downlink ACK / NACK transmission through a DL anchor CC and a DL CC regarded as a DL primary CC.

10. Cross Carrier Scheduling and Setting of DL Extended CC Based on CIF

Each carrier may be classified into a specific carrier type based on a configuration of a DL-UL CC linkage and a physical control channel transmission carrier associated therewith and characteristics of cross carrier scheduling.

When the DL CC transmitting the PDCCH for performing cross-carrier scheduling is specifically set for a cell / base station, and the PHICH is also transmitted through the DL CC, the PDCCH and PHICH are determined in a situation where the base station configures a plurality of DL CCs. The remaining DL CCs except for the transmitted DL CC may be characterized as an extended carrier (DL extended CC). Since the extended carrier does not transmit the PDCCH, it is not necessary to specify the CFI value associated with the PDSCH transmission, and the PCFICH also does not need to be transmitted.

11. Cross-carrier scheduling and establishment of UL primary carrier based on CIF

Based on the configuration of the physical channel transmission carrier associated with the DL-UL CC linkage and the characteristics of cross-carrier scheduling, the UL CC of a specific characteristic may be implicitly or explicitly uniquely.

For example, a PDCCH transmission DL CC that performs cross-carrier scheduling is configured for a transmission station specific or a reception station specific, and an uplink ACK / NACK for a PDSCH transmission designated by the PDCCH is transmitted by a PDCCH. A method of transmitting a PUCCH or a PUSCH through a UL CC set by a link between at least one DL CC and a DL CC / UL CC may be applied. Such a UL CC may be regarded as a UL anchor CC or a UL primary CC.

Scheduling request or feedback information (such as channel state information) may be transmitted through the UL anchor CC or the UL primary CC.

The UL anchor CC or the UL primary CC may be configured through receiving layer specific or transmitting station specific higher layer signaling.

12. PDCCH monitoring set management and use

The PDCCH monitoring set is a set of at least one DL CCs for which the UE should decode a PDCCH (scheduling PDCCH). The UE may use the PDCCH monitoring set to decode or infer whether or not cross carrier scheduling is applied and related parameters.

15 shows an example of a CC set. 4 DL CCs (DL CC # 1, # 2, # 3, # 4) as UE DL CC set, 2 UL CCs (UL CC # 1, # 2) as UE UL CC set, DL CC as PDCCH monitoring set Assume that two (DL CC # 2, # 3) are allocated to the terminal. The UE DL CC set is a set of DL CCs scheduled for the UE to receive a PDSCH, and the UE UL CC set is a set of UL CCs scheduled for the UE to transmit a PUSCH.

The PDCCH monitoring set may be explicitly signaled by being defined as an RRC parameter. The transmitting station (cell or base station or relay station) may signal the receiving station (terminal or relay station) or cell-specifically. Alternatively, the PDCCH monitoring set may be transmitted through L1 / L2 PDCCH control signaling. Alternatively, the PDCCH monitoring set may be implicitly set to a combination of two or more of the RRC parameters. For example, a combination of a UE DL CC set allocated to a terminal and indexes of carriers on which a PDCCH is transmitted in the set, or an index of a UL DL CC set and at least one DL CC in which the PDCCH is not specifically transmitted in the set. It can be expressed in combination.

The PDCCH monitoring set includes: 1) a set representing DL CCs transmitting PDCCHs related to PDSCH (which can be limited to a terminal specific PDSCH) transmission (DL PDCCH monitoring set), and 2) transmitting PDCCHs related to UE specific PUSCH transmission. It may be defined by being divided into a set indicating the DL CCs (UL PDCCH monitoring set). In this case, the configuration of the CIF for the PDSCH transmission (for example, the bit size of the CIF) is set based on the relationship to the PDCCH monitoring set of 1), and the configuration of the CIF for the PUSCH transmission is the PDCCH monitoring of 2). Set based on the relationship to the set.

This will be described in detail below.

(1) If there is one DL CC in the PDCCH monitoring set:

If the DL CC (ie, UE DL CC set) that can be used by the UE is Nd (> 1), and there is one DL CC in the PDCCH monitoring set, scheduling for the remaining DL CCs except for the DL CC designated by the PDCCH monitoring set is performed. The information is decoded on the DL CC designated by the PDCCH monitoring set.

The bit size of the CIF indicating each DL CC may be determined by the Nd. For example, the bit size of CIF may be given as ceil (log ₂ Nd) bits. Alternatively, a state that can represent Nd is implicitly interpreted and mapped to the decoded PDCCH codeword.

DL CCs in the PDCCH monitoring set may be defined to specify only scheduling information of other DL CCs. Or it may be defined to specify scheduling information for Nu UL CCs. Alternatively, scheduling information for both DL CC / UL CC may be specified. In the case of indicating scheduling information for UL CCs, the Nu value may be used as the carrier indicator, or the Nu value may be converted into ceil (log ₂ Nu) and displayed as a bit. Alternatively, scheduling information appearing in each PDCCH may be interpreted by an implicit mapping indicating a Nu state.

(2) When there are two or more DL CCs in the PDCCH monitoring set:

In addition to the matters defined when there is one DL CC in the PDCCH monitoring set, information on whether to allow cross-carrier scheduling between DL CCs in the PDCCH monitoring set may be included.

In case of allowing cross-carrier scheduling between DL CCs in the PDCCH monitoring set, the number of DL CCs (Nd, which may or may not include the PDCCH monitoring set) may be included in the terminal from the viewpoint of the UE. In accordance with this, the size of the PDCCH monitoring set may be operated as if 1. On the other hand, when cross-carrier scheduling is not allowed between DL CCs present in the PDCCH monitoring set, the following method may be applied.

When the DL PDCCH monitoring set and the UL PDCCH monitoring set exist simultaneously in the PDCCH monitoring set, a predetermined rule, for example, a certain number of DL CCs in the PDCCH monitoring set is a subset for the UL CC, and the rest are defined as a subset for the DL CC. The number may be defined and included in the PDCCH monitoring set.

At this time, a method of using CIF for the DL PDCCH monitoring set / UL PDCCH monitoring set is as follows.

In the first method, when the DL PDCCH monitoring set and the UL PDCCH monitoring set are not distinguished in the PDCCH monitoring set, subgrouping (or pairing) a number of DL CCs or UL CCs in decoding the PDCCH for the DL CCs in the PDCCH monitoring set. (pairing) to define cross-carrier scheduling.

The method of subgrouping may be defined in such a manner that specific DL CCs operate independently and specific DL CC groups allow cross-carrier scheduling. The specific DL CC may be a DL CC used for obtaining system information or a reliable DL CC having good reception sensitivity.

The second method is to equally divide and map DL CCs that should receive the PDSCH to DL CCs of the PDCCH monitoring set. At this time, the number of bits that must indicate the entire carrier can be configured to be the minimum. For example, in the case of equal division, the number of bits to indicate the carrier can be equally divided in the form of power of two. If it is not evenly divided or expressed in an exponential form of two, the number of bits to indicate a carrier after splitting may be divided into other values that may be represented by an exponential power of two without splitting evenly. For example, if eight DL CCs are divided into three PDCCH monitoring sets, they may be grouped into [2, 2, 4]. Then, cross-carrier scheduling can be performed with the number of bits that are powers of two. Similarly, it can be applied to subgrouping UL CCs.

Alternatively, different subgroupings may be applied to the DL CC and the UL CC. For example, if the UE is configured to use different numbers of DL CCs and UL CCs, the DL CCs are subgrouped but the UL CCs are processed as a whole without subgrouping to transmit PDCCH codewords in the carriers of all PDCCH monitoring sets. The entire PDCCH monitoring set may be divided into subsets, and the UL PDCCH may be transmitted only on the carrier of the subset (the size of the subset may be one or more).

Once the PDCCH monitoring set is defined, additional information on the UL CC can be estimated. The UL CC may be implicitly estimated while the DL CC is informed by explicit signaling. In this case, the UE can estimate a UL CC that can be used from the PDCCH monitoring set. That is, since the cell-specific DL CC / UL CC link relationship is set, when defining the UL CC to be used by the UE, the UE only for the DL CC of the PDCCH monitoring set and the UL CCs with the cell-specific DL CC / UL CC link relationship is set This is how you define it to use. According to this method, the UL grant for the UL CCs may have a form of individually transmitting for each UL CC in a carrier connected to the DL CC of each DL PDCCH monitoring set. Alternatively, a subset consisting of any one or more DL CCs among DL CCs of the PDCCH monitoring set may be configured to transmit a UL grant for the UL CC. In this case, the DL CC transmitting the corresponding UL grant may be explicitly defined and known in the PDCCH monitoring set. Alternatively, the DL CC transmitting the corresponding UL grant may be implicitly defined in the PDCCH monitoring set. For example, as the carrier indicated in the system band, the index may be defined according to any criterion, such as being selected from the lowest carrier or the highest carrier, the primary carrier, or the anchor carrier.

The PDCCH monitoring set may consider a scheme in which one set has a valid structure for a UE and a scheme in which two or more sets are valid. The configuration of validating only one set is a method of transmitting a PDCCH monitoring set only when the UE intends to redefine its operation when carrier aggregation is applied. On the other hand, when two or more PDCCH monitoring sets are useful, they may be used when updating information on a previous PDCCH monitoring set or controlling individual carrier-specific operations through a combination of different PDCCH monitoring sets.

The PDCCH monitoring set may be divided into a case derived from cell-specific carrier sets or a case consisting only of a UE-specific carrier set regardless of the characteristics thereof. In case of defining cell-specific carrier sets, DL CCs to be used for cross-carrier scheduling in the system are defined in advance (in this case, DL CC / UL CCs can be defined separately) and the UE does not explicitly inform them of this. In the form, when the carrier assignment to the terminal has a form in which at least one cell-specific carrier is included. In this case, the terminal finds a PDCCH monitoring carrier to be used by the terminal from the cell-specific PDCCH monitoring set included. In this case, cross-carrier scheduling may be immediately activated in a carrier allocation step or may be used by using a method of explicitly indicating whether to activate.

16 is a block diagram illustrating a wireless communication system in which an embodiment of the present invention is implemented.

The base station 100 includes a processor 110, a memory 120, and a radio frequency unit (RF) 130.

The processor 110 implements the proposed functions, processes and / or methods. In the above-described embodiment, the operation of the base station may be implemented by the processor 110. The processor 110 may transmit information indicating whether to perform cross carrier scheduling through an upper layer signal or an L1 / L2 PDCCH control signaling. In addition, cross carrier scheduling may be performed. The memory 120 is connected to the processor 110 to store protocols or parameters for multi-carrier operation. The RF unit 130 is connected to the processor 110 and transmits and / or receives a radio signal.

The terminal 200 includes a processor 210, a memory 220, and an RF unit 230.

The processor 210 implements the proposed functions, processes and / or methods. In the above-described embodiment, the operation of the terminal may be implemented by the processor 210. The processor 210 supports the multi-carrier operation, receives information indicating whether to perform cross-carrier scheduling from the base station, and determines whether cross-carrier scheduling is performed based on this information. The downlink data is received or the uplink data is transmitted according to the cross carrier scheduling. Information indicating whether to perform cross carrier scheduling may be received as an upper layer signal.

The memory 220 is connected to the processor 210 to store a protocol or parameter for multi-carrier operation. The RF unit 230 is connected to the processor 210 to transmit and / or receive a radio signal.

Processors 110 and 210 may include application-specific integrated circuits (ASICs), other chipsets, logic circuits, and / or data processing devices. The memory 120, 220 may include read-only memory (ROM), random access memory (RAM), flash memory, memory card, storage medium, and / or other storage device. The RF unit 130 and 230 may include a baseband circuit for processing a radio signal. When the embodiment is implemented in software, the above-described technique may be implemented as a module (process, function, etc.) for performing the above-described function. The module may be stored in the memories 120 and 220 and executed by the processors 110 and 210. The memories 120 and 220 may be inside or outside the processors 110 and 210, and may be connected to the processors 110 and 210 by various well-known means.

In the exemplary system described above, the methods are described based on a flowchart as a series of steps or blocks, but the invention is not limited to the order of steps, and certain steps may occur in a different order or concurrently with other steps than those described above. Can be. In addition, those skilled in the art will appreciate that the steps shown in the flowcharts are not exclusive and that other steps may be included or one or more steps in the flowcharts may be deleted without affecting the scope of the present invention.

The above-described embodiments include examples of various aspects. While not all possible combinations may be described to represent the various aspects, one of ordinary skill in the art will recognize that other combinations are possible. Accordingly, the invention is intended to embrace all other replacements, modifications and variations that fall within the scope of the following claims.

Claims (11)

1. A carrier scheduling method in a multi-carrier system, the method comprising: receiving information indicating whether cross-carrier scheduling is performed from a base station; If it is determined that cross-carrier scheduling is performed based on the information, receiving scheduling information on a second downlink carrier through a first downlink carrier; And receiving downlink data from the second downlink carrier, wherein information indicating whether to perform the cross carrier scheduling is received as an upper layer signal.
2. The method of claim 1, wherein the information indicating whether the cross carrier scheduling is performed is received through a radio resource control (RRC) message.
3. The method of claim 2, wherein the RRC message further includes index information for the first downlink carrier.
4. The method of claim 2, wherein the RRC message further comprises index information for the second downlink carrier.
5. The method of claim 1, wherein the scheduling information for the second downlink carrier received through the first downlink carrier includes a carrier indication field (CIF) indicating the second downlink carrier. .
6. 6. The method of claim 5, wherein the CIF is represented by an absolute index or a logical index of the second downlink carrier.
7. The method of claim 1, further comprising: receiving scheduling information about a first uplink carrier through a first downlink carrier when it is determined that cross carrier scheduling is performed based on the information; And transmitting uplink data to the base station through the first uplink carrier.
8. The method of claim 1, wherein the first downlink carrier is a predetermined downlink carrier.
9. The method of claim 1, wherein the control channel transmitted on the first downlink carrier or the second downlink carrier is set to an independent number of OFDM symbols in the time domain.
10. The method of claim 1, wherein the cross carrier scheduling is performed after N (N is a natural number of 1 or more) subframes from a subframe that receives information indicating whether to perform cross carrier scheduling from the base station.
11. A terminal for performing cross carrier scheduling in a multi-carrier system, the terminal comprising: an RF unit for transmitting and receiving a radio signal; And a processor connected to the RF unit, wherein the processor receives information indicating whether to perform cross-carrier scheduling from a base station, and if it is determined that cross-carrier scheduling is performed based on the information, the processor determines a first downlink carrier. Receiving scheduling information on a second downlink carrier, and receiving downlink data from the second downlink carrier, information indicating whether the cross-carrier scheduling is performed as a higher layer signal.

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